Aktuelles

Dienstag, 18.01.2022: Black Hole and Equipotential Photon Surface Uniqueness in Electrovacuum

Albachiara Cogo (Universität Tübingen)

Equipotential Photon Surfaces are timelike and totally geodesic hypersurfaces in a static spacetime, such that the lapse function and the electric potential are constant at each time on their connected components. They are very interesting objects from the physical point of view and they have mathematical properties that allow us to analyse them adapting techniques developed for the study of Black Hole Horizons. As a result of a project with Borghini and Cederbaum, I will discuss static electrovacuum spacetimes in presence of a connected Horizon or a connected Equipotential Photon Surface, providing a characterization of the Reissner-Nordström spacetime. For this purpose, an approach via potential theory developed by Agostiniani and Mazzieri will be adopted, allowing not to assume the regular foliation of the spacetime by the lapse function, necessary for many other methods. This strategy yields a clear characterization of the spatial slices of the equipotential photon surfaces in sub-extremal, extremal and super-extremal Reissner-Nordström.

Uhrzeit:	12:15
Ort:	C9A03 und Online
Gruppe:	Oberseminar
Einladender:	Graf / Marque

Donnerstag, 20.01.2022: On general position and Del Pezzo surfaces

Sebastian Seemann (Universität Tübingen)

The talk is about Del Pezzo surfaces and the concepts of general and almost general position for up to eight points in P_2. We will also discuss how this is related to smoothings of certain singular Del Pezzo surfaces.

Uhrzeit:	13:00
Ort:	C 2A17; Der Vortrag findet live statt, bei Interesse ist die Zuschaltung per zoom möglich. Die Zugangsdaten erhalten Sie von Elke Nerz.
Gruppe:	Oberseminar Kombinatorische Algebraische Geometrie
Einladender:	Hannah Markwig

Donnerstag, 20.01.2022: Entropy decay for Davies semigroups of a one dimensional quantum lattice

Angela Capel Cuevas (Tübingen)

The mixing time of Markovian dissipative evolutions of open quantum many-body systems can be bounded using optimal constants of certain quantum functional inequalities, such as the logarithmic Sobolev constant, which is equivalent to some form of entropy decay. For classical spin systems, the positivity of such constants follows from a mixing condition on the Gibbs measure, via quasi-factorization results for the entropy. Inspired by the classical case, in this talk we will present a strategy to derive the positivity of the logarithmic Sobolev constant associated to the dynamics of certain quantum systems from some clustering conditions on the Gibbs state of a local, commuting Hamiltonian. Subsequently, we will apply it to show that for a finite-range, translation-invariant commuting Hamiltonian on a spin chain, the Davies semigroup describing the reduced dynamics resulting from the joint Hamiltonian evolution of a spin chain weakly coupled to a large heat bath thermalizes rapidly at any temperature. This, in particular, rigorously establishes the absence of dissipative phase transition for Davies evolutions over translation-invariant spin chains.

Uhrzeit:	16:00
Ort:	online - wenn Sie Zugang haben wollen, schicken Sie bitte eine Nachricht an Elena Kabagema-Bilan
Gruppe:	Oberseminar Mathematical Physics
Einladender:	Capel, Keppeler, Lemm, Pickl, Teufel, Tumulka